<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Document</title>
</head>
<body>
  <script type="text/javascript">
    var arr = [1,2,3,4];
    function p (num) {
    num.push(10)
    console.log(num);
    }
    p(arr)
    console.log(arr);
  </script>
</body>
</html>
